EV Multi-Mode Thermal Management System

ABSTRACT

A multi-mode vehicle thermal management system is provided that allows efficient thermal communication between a refrigerant-based thermal control loop and three non-refrigerant-based thermal control loops, where one of the non-refrigerant-based loops provides temperature control over the vehicle&#39;s passenger cabin, a second of the non-refrigerant-based control loops is thermally coupled to the vehicle&#39;s battery system and the third of the non-refrigerant-based control circuits is thermally coupled to the vehicle&#39;s drive train. The refrigerant-based control loop may be operated either in a heating mode or a cooling mode and is coupled to the vehicle&#39;s HVAC system using a refrigerant-air heat exchanger, and to the battery thermal control loop using refrigerant-fluid heat exchangers.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation-in-part of U.S. patent applicationSer. No. 14/519,182, filed 21 Oct. 2014, the disclosure of which isincorporated herein by reference for any and all purposes.

FIELD OF THE INVENTION

The present invention relates generally to electric vehicles and, moreparticularly, to a thermally efficient and configurable thermalmanagement system.

BACKGROUND OF THE INVENTION

In response to the demands of consumers who are driven both byever-escalating fuel prices and the dire consequences of global warming,the automobile industry is slowly starting to embrace the need forultra-low emission, high efficiency cars. While some within the industryare attempting to achieve these goals by engineering more efficientinternal combustion engines, others are incorporating hybrid orall-electric drive trains into their vehicle line-ups. To meet consumerexpectations, however, the automobile industry must not only achieve agreener drive train, but must do so while maintaining reasonable levelsof performance, range, reliability, and cost.

Electric vehicles, due to their reliance on rechargeable batteries,require a relatively sophisticated thermal management system to insurethat the batteries remain within their desired operating temperaturerange. Furthermore, in addition to controlling battery temperature thethermal management system must also be capable of heating and coolingthe passenger cabin while not unduly affecting the vehicle's overalloperating efficiency.

A variety of approaches have been taken to try and meet these goals. Forexample, U.S. Pat. No. 6,360,835 discloses a thermal management systemfor use with a fuel-cell-powered vehicle, the system utilizing both lowand high temperature heat transfer circuits that share a common heattransfer medium, the dual circuits required to adequately cool thevehicle's exothermic components and heat the vehicle's endothermiccomponents.

U.S. Pat. No. 7,789,176 discloses a thermal management system thatutilizes multiple cooling loops and a single heat exchanger. In anexemplary embodiment, one cooling loop is used to cool the energystorage system, a second cooling loop corresponds to the HVAC subsystem,and a third cooling loop corresponds to the drive motor cooling system.The use of a heater coupled to the first cooling loop is also disclosed,the heater providing a means for insuring that the batteries are warmenough during initial vehicle operation or when exposed to very lowambient temperatures.

U.S. Pat. No. 8,336,319 discloses an EV dual mode thermal managementsystem designed to optimize efficiency between two coolant loops, thefirst cooling loop in thermal communication with the vehicle's batteriesand the second cooling loop in thermal communication with at least onedrive train component such as an electric motor or an inverter. Thedisclosed system uses a dual mode valve system to configure the thermalmanagement system between a first mode and a second mode of operation,where in the first mode the two cooling loops operate in parallel and inthe second mode the two cooling loops operate in series.

Although the prior art discloses numerous techniques for maintaining thetemperature of the battery pack and other vehicle subsystems, animproved thermal management system is needed that efficiently controlsthe temperature of each of the vehicle's thermal systems whileoptimizing overall vehicle operating efficiency. The present inventionprovides such a thermal management system.

SUMMARY OF THE INVENTION

The present invention provides a vehicle thermal management system thatutilizes three separate thermal control circuits to provide an efficientthermal control system. The system includes (i) a passenger cabinthermal control loop comprising a first circulation pump and aliquid-air heat exchanger, where the first circulation pump circulates afirst heat transfer fluid within the passenger cabin thermal controlloop and through the liquid-air heat exchanger, and where the passengercabin thermal control loop provides temperature control of a vehiclepassenger cabin; (ii) a battery thermal control loop comprising a secondcirculation pump that circulates a second heat transfer fluid within thebattery thermal control loop, where the battery thermal control loop isthermally coupled to a vehicle battery pack, and where the passengercabin thermal control loop operates in parallel with and independent ofthe battery thermal control loop; (iii) a drive train control loopcomprising a third circulation pump that circulates a third heattransfer fluid within the drive train control loop, where the drivetrain control loop is thermally coupled to at least one drive traincomponent, and where the passenger cabin thermal control loop operatesin parallel with and independent of the drive train thermal controlloop, and where the battery thermal control loop operates in parallelwith and independent of the drive train thermal control loop; (iv) arefrigerant-based thermal control loop comprised of a refrigerant, acompressor, and a condenser/evaporator; (v) a refrigerant-air heatexchanger coupled to the refrigerant-based thermal control loop by afirst expansion valve, where the refrigerant-air heat exchanger isthermally coupled to a vehicle HVAC system; (vi) a refrigerant valveoperable in at least two modes; and (vii) a refrigerant-fluid heatexchanger coupled to the battery thermal control loop, where therefrigerant valve in a first mode directs the refrigerant through therefrigerant-air heat exchanger and the first expansion valve, and wherethe refrigerant valve in a second mode directs the refrigerant throughthe refrigerant-fluid heat exchanger which, in turn, heats the secondheat transfer fluid within the battery thermal control loop.

The refrigerant-based thermal control loop may further include a secondrefrigerant-fluid heat exchanger coupled to the refrigerant-basedthermal control loop by a second expansion valve, where the secondrefrigerant-fluid heat exchanger is thermally coupled to the batterythermal control loop.

The system may include (i) a refrigerant by-pass valve; and (ii) asecond expansion valve interposed between the refrigerant-fluid heatexchanger and the condenser/evaporator, where when the refrigerant valveis in the first mode the refrigerant by-pass valve is configured toallow the refrigerant in the refrigerant-based thermal control loop toby-pass the second expansion valve, and where when the refrigerant valveis in the second mode the refrigerant by-pass valve is configured toallow the refrigerant in the refrigerant-based thermal control loop toflow through the second expansion valve. The by-pass valve and thesecond expansion valve may be combined into a single electronicexpansion valve.

The refrigerant-based thermal control loop may further include arefrigerant by-pass valve, where the refrigerant by-pass valve in afirst operational mode couples the refrigerant-fluid heat exchanger tothe refrigerant-based thermal control loop, and where the secondaryrefrigerant by-pass valve in a second operational mode decouples therefrigerant-fluid heat exchanger from the refrigerant-based thermalcontrol loop.

The passenger cabin thermal control loop may further include asupplemental electric heater configured to heat the first heat transferfluid within the passenger cabin thermal control loop when electricalpower is connected to the supplemental electric heater.

In another aspect, the system may include a radiator coupled to thedrive train thermal loop. The system may include a diverter valve, wherethe diverter valve in a first position couples the radiator to the drivetrain thermal loop and allows at least a portion of the third heattransfer fluid to flow through the radiator, and where the divertervalve in a second position decouples the radiator from the drive trainthermal loop and allows the third heat transfer fluid within the drivetrain thermal loop to bypass the radiator. In the first position, thediverter valve may be configured to allow a second portion of the thirdheat transfer fluid to bypass the radiator. In a third position, thediverter valve may be configured to couple the radiator to the drivetrain thermal loop and allow the third heat transfer fluid to flowthrough the radiator while preventing the second portion of the thirdheat transfer fluid from bypassing the radiator. The system may furtherinclude a fan configured to force air through the radiator.

In another aspect, the vehicle battery pack may include a plurality ofbatteries and a plurality of cooling conduits in thermal communicationwith the plurality of batteries, where the second heat transfer fluidflows through the plurality of cooling conduits. The vehicle drive traincomponent may be selected from the group consisting of a motor, agearbox, and a power inverter. A DC/DC converter may be thermallycoupled to the drive train control loop.

In another aspect, the first and/or the second and/or the third heattransfer fluid may be selected from the group of fluids consisting ofwater and water with an additive, where the additive may be selectedfrom the group consisting of ethylene glycol and propylene glycol.

In another aspect, the system may include a coolant reservoir, where thethird heat transfer fluid within the drive train thermal loop flows intoand out of the coolant reservoir.

A further understanding of the nature and advantages of the presentinvention may be realized by reference to the remaining portions of thespecification and the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

It should be understood that the accompanying figures are only meant toillustrate, not limit, the scope of the invention and should not beconsidered to be to scale. Additionally, the same reference label ondifferent figures should be understood to refer to the same component ora component of similar functionality.

FIG. 1 provides a perspective view of a battery pack and the vehiclechassis to which it is to be mounted;

FIG. 2 illustrates an exemplary battery pack cooling system inaccordance with the prior art;

FIG. 3 illustrates an alternate battery pack cooling system inaccordance with the prior art;

FIG. 4 illustrates an alternate battery pack cooling system inaccordance with the prior art, the illustrated system utilizing both aradiator and a heat exchanger as described relative to FIGS. 2 and 3,respectively;

FIG. 5 schematically illustrates a preferred embodiment of the thermalmanagement system of the invention;

FIG. 6 illustrates an alternate configuration of the preferred thermalmanagement system shown in FIG. 5 in which the passenger cabin thermalcontrol loop is coupled to the battery pack thermal control loop;

FIG. 7 illustrates an alternate configuration of the preferred thermalmanagement system shown in FIG. 5 in which the battery pack thermalcontrol loop is coupled to the drive train thermal control loop;

FIG. 8 illustrates an alternate configuration of the preferred thermalmanagement system shown in FIG. 5 in which the passenger cabin thermalcontrol loop is coupled to the battery pack thermal control loop which,in turn, is coupled to the drive train thermal control loop;

FIG. 9 provides a block diagram of an exemplary control system for usewith the thermal management system shown in FIGS. 5-8;

FIG. 10 illustrates a modification of the preferred thermal managementsystem shown in FIG. 5 in which each four-way valves is replaced with apair of three-way valves;

FIG. 11 illustrates the thermal management system shown in FIG. 10,reconfigured to serially couple the passenger cabin thermal control loopto the battery pack thermal control loop which, in turn, is coupled tothe drive train thermal control loop;

FIG. 12 illustrates a modification of the preferred thermal managementsystem shown in FIGS. 5-8 in which one of the four-way valves iseliminated, thereby causing the drive train thermal control loop tooperate independently of the passenger cabin thermal control loop andthe battery pack thermal control loop;

FIG. 13 illustrates a modification of the preferred thermal managementsystem shown in FIGS. 5-8 in which one of the four-way valves iseliminated, thereby causing the passenger cabin thermal control loop tooperate independently of the battery pack thermal control loop and thedrive train thermal control loop;

FIG. 14 illustrates a modification of the preferred thermal managementsystem shown in FIGS. 5-8 in which both four-way valves are eliminated,thereby causing independent operation of the passenger cabin thermalcontrol loop, the battery pack thermal control loop and the drive trainthermal control loop;

FIG. 15 illustrates a modification of the thermal management systemshown in FIG. 13 in which the refrigeration system is used as a heatpump to heat the battery pack thermally coupled to the battery thermalcontrol loop;

FIG. 16 illustrates a modification of the thermal management systemshown in FIG. 14 in which the refrigeration system is used as a heatpump to heat the battery pack thermally coupled to the battery thermalcontrol loop;

FIG. 17 illustrates a modification of the thermal management systemshown in FIG. 15 utilizing an alternate passenger cabin heating system;and

FIG. 18 illustrates a modification of the thermal management systemshown in FIG. 16 utilizing an alternate passenger cabin heating system.

DESCRIPTION OF THE SPECIFIC EMBODIMENTS

As used herein, the singular forms “a”, “an” and “the” are intended toinclude the plural forms as well, unless the context clearly indicatesotherwise. The terms “comprises”, “comprising”, “includes”, and/or“including”, as used herein, specify the presence of stated features,steps, operations, elements, and/or components, but do not preclude thepresence or addition of one or more other features, steps, operations,elements, components, and/or groups thereof. As used herein, the term“and/or” and the symbol “/” are meant to include any and allcombinations of one or more of the associated listed items.Additionally, while the terms first, second, etc. may be used herein todescribe various steps or calculations, these steps or calculationsshould not be limited by these terms, rather these terms are only usedto distinguish one step or calculation from another. For example, afirst calculation could be termed a second calculation, and, similarly,a first step could be termed a second step, without departing from thescope of this disclosure.

In the following text, the terms “battery”, “cell”, and “battery cell”may be used interchangeably and may refer to any of a variety ofdifferent battery configurations and chemistries. Typical batterychemistries include, but are not limited to, lithium ion, lithium ionpolymer, nickel metal hydride, nickel cadmium, nickel hydrogen, nickelzinc, and silver zinc. The term “battery pack” as used herein refers toan assembly of one or more batteries electrically interconnected toachieve the desired voltage and capacity, where the battery assembly istypically contained within an enclosure. The terms “electric vehicle”and “EV” may be used interchangeably and may refer to an all-electricvehicle, a plug-in hybrid vehicle, also referred to as a PHEV, or ahybrid vehicle, also referred to as a HEV, where a hybrid vehicleutilizes multiple sources of propulsion including an electric drivesystem. The terms “thermal control circuit” and “thermal control loop”may be used interchangeably.

FIG. 1 provides a perspective view of a battery pack 101 configured tobe mounted under vehicle chassis 103. It should be understood that thepresent invention is not limited to a specific battery pack mountingscheme, battery pack size, or battery pack configuration.

FIG. 2 illustrates an exemplary battery thermal management system 200 inaccordance with the prior art. In system 200, the temperature of thebatteries within battery pack 101 is controlled by pumping a thermaltransfer medium, e.g., a liquid coolant, through a plurality of coolingconduits 201 integrated into battery pack 101. Conduits 201, which arefabricated from a material with a relatively high thermal conductivity,are positioned within pack 101 in order to optimize thermalcommunication between the individual batteries, not shown, and theconduits, thereby allowing the temperature of the batteries to beregulated by regulating the flow of coolant within conduits 201 and/orregulating the transfer of heat from the coolant to another temperaturecontrol system. In the illustrated embodiment, the coolant withinconduits 201 is pumped through a radiator 203 using a pump 205. A blowerfan 207 may be used to force air through radiator 203, for example whenthe car is stationary or moving at low speeds, thus insuring that thereis an adequate transfer of thermal energy from the coolant to theambient environment. System 200 may also include a heater 209, e.g., aPTC heater, that may be used to heat the coolant within conduits 201,and thus heat the batteries within pack 101.

FIG. 3 illustrates an alternate battery pack thermal management system300. In system 300 the coolant within conduits 201 is coupled to asecondary thermal management system 301 via a heat exchanger 303.Preferably thermal management system 301 is a refrigeration system andas such, includes a compressor 305 to compress the low temperature vaporin refrigerant line 307 into a high temperature vapor and a condenser309 in which a portion of the captured heat is dissipated. After passingthrough condenser 309, the refrigerant changes phases from vapor toliquid, the liquid remaining at a temperature below the saturationtemperature at the prevailing pressure. The refrigerant then passesthrough a dryer 311 that removes moisture from the condensedrefrigerant. After dryer 311, refrigerant line 307 is coupled to heatexchanger 303 via thermal expansion valve 313 which controls the flowrate of refrigerant into heat exchanger 303. Additionally, in theillustrated system a blower fan 315 is used in conjunction withcondenser 309 to improve system efficiency.

In a typical vehicle configuration, thermal management system 301 isalso coupled to the vehicle's heating, ventilation and air conditioning(HVAC) system. In such a system, in addition to coupling refrigerantline 307 to heat exchanger 303, line 307 may also be coupled to the HVACevaporator 317. A thermal expansion valve 319 is preferably used tocontrol refrigerant flow rate into the evaporator. A heater, for examplea PTC heater 321 integrated into evaporator 317, may be used to providewarm air to the passenger cabin. In a conventional HVAC system, one ormore fans 323 are used to circulate air throughout the passenger cabin,where the circulating air may be ambient air, air cooled via evaporator317, or air heated by heater 321.

In some electric vehicles, battery pack cooling is accomplished using acombination of a radiator such as that shown in FIG. 2, and a heatexchanger such as that shown in FIG. 3. FIG. 4 illustrates such aconventional cooling system. In system 400, the coolant passing throughbattery pack 101 via conduits 201 may be directed through eitherradiator 401 or heat exchanger 303. Valve 403 controls the flow ofcoolant through radiator 401. Preferably a blower fan 405 is included insystem 400 as shown, thus providing means for forcing air through theradiator when necessary, for example when the car is stationary.

FIG. 5 provides a schematic overview of the thermal management system ofthe invention, this figure illustrating thermal communications betweenrefrigeration loop 501 and the system's three independent thermalcontrol loops corresponding to the passenger cabin thermal control loop503, the battery thermal control loop 505 and the drive train thermalcontrol loop 507. The use of three independent thermal control circuitsalong with the refrigeration circuit allows the thermal managementsystem to efficiently regulate the temperature within the passengercabin, the battery pack and the drive train, specifically utilizing theheat generated within one subsystem to heat another subsystem. In thepreferred embodiment shown in FIG. 5, independent thermal control loops503, 505 and 507 utilize the same non-gaseous, heat transfer fluid,thereby allowing the control loops to operate either independently or inseries as described below. Preferably the heat transfer fluid iswater-based, e.g., pure water or water that includes an additive such asethylene glycol or propylene glycol, although a non-water-based, heattransfer fluid may also be used in control loops 503, 505 and 507.

The passenger cabin includes a HVAC system, described in detail below,which provides the vehicle's occupants means for regulating cabintemperature. Coupled to battery thermal control loop 505 is a batterypack 509 that includes at least one, and typically a plurality ofbatteries (e.g., tens, hundreds, or thousands of batteries), containedwithin a battery pack enclosure. In at least one configuration thebatteries are cylindrically-shaped, for example utilizing an 18650form-factor, and are positioned within the battery pack so that thecylindrical axis of each battery is substantially perpendicular to thelower battery pack enclosure panel as well as the surface of the road.Cooling conduits 511, preferably deformable cooling conduits, whichcontain the heat transfer fluid (e.g., water), are in thermalcommunication with the batteries. In at least one preferred embodiment,the cooling conduits are aligned with the battery pack's lower panel,resulting in the coolant within the conduits flowing in a directionsubstantially perpendicular to the axes of the cylindrical batteries. Byregulating the flow of the coolant (e.g., the heat transfer fluid)within the cooling conduits and/or regulating the transfer of heat fromthe coolant to another temperature control system, the temperature ofthe batteries may be regulated so that they remain within theirpreferred operating range. Preferably a thermal insulator (e.g., an airgap or one or more layers of a material with a low thermal conductivity)is used to limit the unintended transfer of thermal energy from thebatteries and the battery cooling conduits to the battery packenclosure. An example of a suitable battery pack cooling system isdescribed in co-assigned U.S. patent application Ser. No. 14/148,933,filed 7 Jan. 2014, the disclosure of which is incorporated herein byreference for any and all purposes. It should be understood that in somevehicle configurations one or more additional components may bethermally coupled to thermal control loop 505.

Thermal control loop 507 is thermally coupled to drive train 513. Drivetrain 513 includes one or more motors, typically three phase alternatingcurrent (i.e., AC) motors, which are used to provide propulsive power tothe vehicle. The portion of the drive train 513 that is thermallyregulated may also include a transmission and/or a power inverter, forexample as described in co-assigned U.S. patent application Ser. No.14/176,053, filed 8 Feb. 2014, the disclosure of which is incorporatedherein by reference for any and all purposes. The power inverterconverts the direct current (i.e., DC) power from battery pack 509 tomatch the power requirements of the propulsion motor(s). Thetransmission may be a single speed, fixed gear transmission or amulti-speed transmission.

In the illustrated configuration, a DC/DC converter 515 is alsothermally coupled to control loop 507. The DC/DC converter 515 is usedto convert the output of battery pack 509 to a voltage more suitable foruse with the vehicle's various electrical accessories and auxiliarysystems (e.g., exterior and interior lighting, audio system, navigationsystem, blower fans, etc.).

Within drive train thermal control loop 507 the heat transfer fluid iscirculated using coolant pump 517. Preferably coolant pump 517 iscapable of circulating the heat transfer fluid within the control loopat a flow rate of at least 15 liters per minute (lpm), both when controlloop 507 is operated independently of the other thermal circuits andwhen control loop 507 is coupled to another control loop as describedbelow. Thermal control loop 507 also includes a coolant reservoir 519.Preferably reservoir 519 is a high by-pass reservoir that not onlydeaerates the coolant within the control loop, but also provides aconvenient means for adding coolant to the system.

In order to passively cool the components that are thermally coupled tocontrol circuit 507, components such as the motor, power inverter,gearbox and/or the DC/DC converter, the coolant is circulated throughradiator 521. If there is insufficient air flow through radiator 521 toprovide the desired level of passive cooling, for example when thevehicle is stopped or driving at slow speeds, a fan 523 may be used toforce air through the radiator. Preferably the control loop alsoincludes a valve 525, also referred to herein as a diverter valve, thatallows radiator 521 to be decoupled, or partially decoupled, from loop507.

As noted above, thermal control loops 503, 505 and 507 may be operatedindependently as illustrated in FIG. 5, or operated in series asdescribed and illustrated below. Accordingly, in addition to circulationpump 517 that is coupled to circuit 507, circulation pumps must also beincorporated into loops 503 and 505. FIG. 5 shows a single circulationpump 527 incorporated into loop 505 and a single circulation pump 529incorporated into loop 503. It will be appreciated that more than onecirculation pump may be incorporated into any of the thermal controlloops. Preferably, and as described above, each circulation pump iscapable of circulating the heat transfer fluid contained within thecorresponding control loop at a flow rate of at least 15 liters perminute (lpm), both when operating alone and when the correspondingcontrol loop is serially coupled to one or more other thermal controlloops.

The heat transfer fluid within the passenger cabin thermal control loop503, which is circulated using pump 529, flows through a liquid-air heatexchanger 531. Preferably a supplemental electric heater 533 is alsothermally coupled to control loop 503, thereby providing an additionalmeans for heating the heat transfer fluid within loop 503 and thusheating the passenger cabin to the desired level.

In the preferred embodiment of the present invention, refrigerant-basedthermal control loop 501 serves multiple purposes and can be used ineither a conventional cooling mode or in a non-conventional heat pumpmode. Included in loop 501 is a compressor 535, used to compress the lowtemperature vapor in the refrigerant line into a high temperature vapor,and an accumulator 537 that insures that only vapor passes intocompressor 535. Valve 539 determines the direction of flow of therefrigerant within loop 501, and thus to a degree determines whether therefrigeration system is being used in a heat pump mode or in aconventional cooling mode.

Operating in a conventional mode, the refrigerant passes throughexpansion valve 541 prior to flowing through evaporator 543, whereevaporator 543 is integrated into the passenger cabin's HVAC system. Theair that is cooled by the refrigeration system's evaporator 543 iscirculated throughout the passenger cabin using fan 545. After flowingthrough evaporator 543, accumulator 537 and compressor 535, therefrigerant passes through heat exchanger 547, also referred to hereinas a condenser/evaporator due to its dual functionality as described indetail below. It will be appreciated that in this operational mode, heatexchanger 547 is performing as an air cooled condenser. Preferably thesystem also includes a blower fan 549 that may be used to force airthrough heat exchanger 547 if the vehicle is traveling at a low speed,or altogether stopped, thus insuring adequate heat transfer from therefrigerant to the ambient environment. Note that in this mode, by-passvalve 551 allows the refrigerant to by-pass expansion valve 553. Ifdesired, the functionality of by-pass valve 551 and expansion valve 553may be combined into a single electronic expansion valve.

When operating in the conventional mode, the refrigerant line is alsocoupled via expansion valve 555 to heat exchanger 557, where expansionvalves 541 and 555 may be used to regulate the flow of refrigerant. Heatexchanger 557, which is a refrigerant/liquid exchanger, may also bereferred to herein as a chiller. As shown, chiller 557 is coupled tobattery thermal control loop 505, thus allowing battery pack 509 to becooled by the heat transfer fluid within circuit 505. Expansion valve555 determines, at least in part, the amount of cooling provided by therefrigeration system to battery thermal control loop 505.

As noted above and illustrated in FIG. 5, the refrigeration system mayalso operate in a heat pump mode by altering the flow of refrigerantusing valve 539. In this mode, the refrigerant passing through heatexchanger 559 is used to heat the heat transfer fluid within HVACthermal control loop 503. Once heated, the heat transfer fluid iscirculated through heat exchanger 531 which, in turn, heats thepassenger cabin. Fan 545, or a different fan (not shown), is preferablyused to circulate the heated air through the passenger cabin. Whenoperating in this mode, the setting of by-pass valve 551 is changed sothat the refrigerant can pass through expansion valve 553 prior toflowing through heat exchanger 547. Note that in this mode, heatexchanger 547 performs as an evaporator rather than as a condenser.Preferably the system also includes a by-pass valve 560 that provides analternate refrigerant path around heat exchanger 559, thereby providinga simple means for limiting the amount of heat added to the heattransfer fluid by the heat exchanger. It will be appreciated that byusing the refrigeration system as a heat pump and transferring heat fromthe refrigerant to the heat transfer fluid via heat exchanger 559, thecooling capacity of the AC system is increased.

In addition to using refrigeration control loop 501 to cool battery pack509, as necessary, and either heat or cool the passenger cabin, thepreferred thermal management system of the invention may be configuredin a variety of ways, thus allowing the thermal system to be optimized.In the configuration shown in FIG. 5, thermal control loops 503, 505 and507 are each operated independently. As a result, the temperature of thedrive train components 513 and DC/DC converter 515 are passively cooledusing radiator 521, where the amount of cooling is preferably controlledeither by varying the flow rate using circulating pump 517 or varyingcoolant flow through radiator 521 using valve 525. When operating in afully independent mode, the temperature of the coolant within batterypack thermal control circuit 505 is varied by controlling the amount ofcooling provided via the refrigeration system and heat exchanger 557.

When the passenger thermal control loop 503 is operating in a fullyindependent mode, cooling is provided by the refrigeration system andevaporator 543. In this configuration, in order to heat the passengercabin the heat transfer fluid within circuit 503 may either be heatedusing supplemental electric heater 533 or using the refrigeration systemoperating as a heat pump, where heat is transferred using heat exchanger559.

FIG. 6 illustrates an alternate operational mode of the preferredthermal management system. In this configuration four-way valve 561 isaltered in order to combine passenger cabin thermal control loop 503with battery pack thermal control loop 505. In this configuration drivetrain thermal control loop 507 operates independently of the other twothermal control circuits. This operational mode provides severalbenefits. First, when the battery pack is running hot, thisconfiguration allows excess battery pack heat to be transferred to thepassenger cabin HVAC system, thus providing a means for heating the heattransfer fluid within circuit 503 and heat exchanger 531 withoutactivating supplemental electric heater 533 or using the refrigerationsystem as a heat pump. Second, when the battery pack is cold, heat fromthermal loop 503 may be used to heat the batteries within pack 509 totheir optimum operating range, where the heat in thermal loop 503 may begenerated either by supplemental electric heater 533 or refrigerationsystem 501 operating as a heat pump. Note that if battery heating isprovided by the refrigeration system 501 operating as a heat pump anddumping heat into the heat transfer fluid via heat exchanger 559,supplemental heater 533 becomes unnecessary. As a result, the batteriescan be heated to reach their optimum operating temperature withoutimpacting vehicle efficiency by activating the supplemental heater. Itwill be appreciated that if the battery pack requires heat, but addingheat to the passenger cabin is undesirable, a temperature blend door inthe HVAC system, represented as dashed line 571 in the figures, may beused to prevent, or regulate, air circulated by HVAC fan 545 fromflowing past heat exchanger 531 and through the passenger cabin.

FIG. 7 illustrates another operational mode of the preferred thermalmanagement system in which four-way valve 563 is altered in order tocombine battery pack thermal control loop 505 with drive train thermalcontrol loop 507. In this operational mode passenger cabin thermalcontrol loop 503 operates independently of the other two thermal controlcircuits. As a result of this operational mode two techniques may beused, alone or in combination, to cool battery pack 509. First, the heattransfer fluid within the thermal loop may be cooled using refrigerationsystem 501 and heat exchanger 557. Second, the heat transfer fluid maybe cooled by passing through radiator 521.

FIG. 8 illustrates a third operational mode of the thermal managementsystem in which both four way valves 561 and 563 are opened, therebycoupling passenger cabin control loop 503 to battery pack control loop505 which, in turn, is coupled to drive train control loop 507. As aresult, the battery pack may be cooled and heat transferred out of thebattery pack using the refrigeration system 501, and/or heat exchanger531, and/or radiator 521.

FIG. 9 is a block diagram of an exemplary control system 900 for usewith the thermal management system shown in FIGS. 5-8. Control system900 includes a system controller 901. System controller 901 may be thesame controller used to perform other vehicle functions, i.e., systemcontroller 901 may be a vehicle system controller that may be used tocontrol any of a variety of vehicle subsystems, e.g., navigation system,entertainment system, suspension (e.g., air suspension), batterycharging, vehicle performance monitors, etc. Alternately, systemcontroller 901 may be separate from the vehicle's system controller.System controller 901 includes a central processing unit (CPU) 903 and amemory 905. Memory 905 may be comprised of EPROM, EEPROM, flash memory,RAM, a solid state disk drive, a hard disk drive, or any other memorytype or combination of memory types. Memory 905 may be used to store thepreset operating temperature ranges for battery pack 509, drive train513 and/or DC/DC converter 515. If the vehicle uses a touch-screen orsimilar display means 907 as the user interface, controller 901 may alsoinclude a graphical processing unit (GPU) 909. CPU 903 and GPU 909 maybe separate or contained on a single chip set.

Coupled to controller 901 are a plurality of temperature sensors thatmonitor the temperatures of various components and subsystems under thecontrol of the thermal control system. For example, battery pack 509 mayinclude one or more temperature sensors 565 that monitor battery packtemperature. Other components and subsystems may also includetemperature sensors, e.g., sensor 567 that monitors drive train 513.Temperature sensors may also be used to monitor the temperature of theheat transfer fluid within thermal control loops 503, 505 and 507, i.e.,temperature sensors 569. Temperature/pressure sensors 570 are alsopreferably used to monitor the state of the refrigerant in thermalcontrol loop 501. Lastly, the temperature within the passenger cabin(sensor 911), the ambient temperature (sensor 913), and the sun load(sensor 915) may also be monitored. Also coupled to controller 901 is aHVAC system interface 917 that allows the desired passenger cabintemperature to be set by the driver and/or passengers, where the desiredtemperature may be configured to either be set by zone or a singletemperature for the entire cabin. The HVAC system interface 917 may be aHVAC dedicated interface, e.g., temperature control switches mountedwithin the passenger cabin, or may utilize a common user interface suchas display interface 907.

As described above, the thermal control system of the invention uses avariety of valves and other components to maintain each of the vehicle'ssubsystems (e.g., battery pack, drive train components, passenger cabin,etc.) within their desired temperature range while optimizing overallsystem efficiency. Accordingly, coupled to and controlled by controller901 are flow control valves 525, 539, 551, 560, 561 and 563; expansionvalves 541, 553 and 555; compressor 535; HVAC temperature blend door571; heat transfer fluid circulating pumps 517, 527 and 529; blower fans523, 545 and 549; and heater 533.

In will be appreciated that the embodiment described above may bemodified while still retaining many of the benefits of the preferredapproach. For example, four-way valve 561 may be replaced with a pair ofthree-way valves. Similarly, four-way valve 563 may be replaced with apair of three-way valves. FIGS. 10 and 11 illustrate an embodiment inwhich both four-way valves are replaced. FIG. 10 illustrates aconfiguration similar to that shown in FIG. 5 in which thermal controlcircuits 503, 505 and 507 are operated independently of one another.FIG. 11 illustrates an operational mode similar to that shown in FIG. 8in which thermal control circuits 503, 505 and 507 are serially coupled.It should be understood that valves 1001-1004 may also be configured toprovide the same operational modes as illustrated in FIGS. 6 and 7.

FIG. 12 illustrates another modification of the embodiment shown inFIGS. 5-8 in which four-way valve 563 is eliminated. As a result ofeliminating valve 563, drive train thermal control loop 507 alwaysoperates independently of passenger cabin thermal control loop 503 andbattery pack thermal control loop 505. In this configuration drive trainthermal control loop 507 is also independent of refrigeration thermalcontrol loop 501. Note that due to the inclusion of four-way valve 561,the passenger cabin and battery pack thermal circuits may be operatedindependently of one another, i.e., parallel operation, or serially asshown in FIG. 6. It will be appreciated that four-way valve 561 may bereplaced with a pair of three-way valves as shown in FIGS. 10 and 11.

FIG. 13 illustrates yet another modification of the embodiment shown inFIGS. 5-8 in which four-way valve 561 is eliminated. As a result ofeliminating valve 561, passenger cabin thermal control loop 503 alwaysoperates independently of battery pack thermal control loop 505 anddrive train thermal control loop 507. Preferably in this embodiment asupplemental heater 1301 is included in the battery thermal control loop505, thus providing a means of actively heating the batteries withinpack 509. Note that due to the inclusion of four-way valve 563, thebattery pack and drive train thermal circuits may be operatedindependently of one another, i.e., parallel operation, or serially asshown in FIG. 7. It will be appreciated that four-way valve 563 may bereplaced with a pair of three-way valves as shown in FIGS. 10 and 11.

FIG. 14 illustrates yet another modification of the embodiment shown inFIGS. 5-8 in which four-way valves 561 and 563 are eliminated. Theelimination of both four-way valves results in independent operation ofthe passenger cabin thermal control loop 503, the battery pack thermalcontrol loop 505 and the drive train thermal control loop 507. As in theembodiment shown in FIG. 13, preferably a supplemental heater 1301 isincluded in the battery thermal control loop 505 in order to provide ameans for actively heating the batteries as deemed necessary.

As noted above, in order to provide active battery heating for theembodiments shown in FIGS. 13 and 14, a supplemental heater 1301 isincorporated into the battery thermal control loop 505. FIGS. 15 and 16illustrate an alternate approach of active battery heating, based onFIGS. 13 and 14, which utilizes heat exchanger 559 and the refrigerationloop 501 rather than supplemental heater 1301 to heat the heat transferfluid within the battery loop. Note that if desired, supplemental heater1301 may also be added to the embodiments shown in FIGS. 15 and 16.Furthermore, while passenger cabin heating can be provided usingsupplemental heater 533 as shown in FIGS. 15 and 16, preferably anelectric air heater 1701, e.g., incorporated into evaporator assembly543, is used for passenger cabin heating as shown in FIGS. 17 and 18.

Systems and methods have been described in general terms as an aid tounderstanding details of the invention. In some instances, well-knownstructures, materials, and/or operations have not been specificallyshown or described in detail to avoid obscuring aspects of theinvention. In other instances, specific details have been given in orderto provide a thorough understanding of the invention. One skilled in therelevant art will recognize that the invention may be embodied in otherspecific forms, for example to adapt to a particular system or apparatusor situation or material or component, without departing from the spiritor essential characteristics thereof. Therefore the disclosures anddescriptions herein are intended to be illustrative, but not limiting,of the scope of the invention.

What is claimed is:
 1. A multi-mode vehicle thermal management system,comprising: a passenger cabin thermal control loop comprising a firstcirculation pump and a liquid-air heat exchanger, wherein said firstcirculation pump circulates a first heat transfer fluid within saidpassenger cabin thermal control loop and through said liquid-air heatexchanger, and wherein said passenger cabin thermal control loopprovides temperature control of a vehicle passenger cabin; a batterythermal control loop comprising a second circulation pump, wherein saidsecond circulation pump circulates a second heat transfer fluid withinsaid battery thermal control loop, wherein said battery thermal controlloop is thermally coupled to a vehicle battery pack, and wherein saidpassenger cabin thermal control loop operates in parallel with andindependent of said battery thermal control loop; a drive train controlloop comprising a third circulation pump, wherein said third circulationpump circulates a third heat transfer fluid within said drive traincontrol loop, wherein said drive train control loop is thermally coupledto at least one drive train component, wherein said passenger cabinthermal control loop operates in parallel with and independent of saiddrive train thermal control loop, and wherein said battery thermalcontrol loop operates in parallel with and independent of said drivetrain thermal control loop; a refrigerant-based thermal control loop,wherein said refrigerant-based thermal control loop is comprised of arefrigerant, a compressor, and a condenser/evaporator; a refrigerant-airheat exchanger coupled to said refrigerant-based thermal control loop bya first expansion valve, wherein said refrigerant-air heat exchanger isthermally coupled to a vehicle HVAC system; a refrigerant valve operablein at least two modes; and a refrigerant-fluid heat exchanger coupled tosaid battery thermal control loop, wherein said refrigerant valve in afirst mode directs said refrigerant through said refrigerant-air heatexchanger and said first expansion valve, wherein said refrigerant valvein a second mode directs said refrigerant through said refrigerant-fluidheat exchanger, and wherein said second heat transfer fluid within saidbattery thermal control loop is heated when said refrigerant is directedthrough said refrigerant-fluid heat exchanger.
 2. The multi-mode vehiclethermal management system of claim 1, further comprising a secondrefrigerant-fluid heat exchanger coupled to said refrigerant-basedthermal control loop by a second expansion valve, wherein said secondrefrigerant-fluid heat exchanger is thermally coupled to said batterythermal control loop.
 3. The multi-mode vehicle thermal managementsystem of claim 1, further comprising: a refrigerant by-pass valve; anda second expansion valve interposed between said refrigerant-fluid heatexchanger and said condenser/evaporator, wherein when said refrigerantvalve is in said first mode said refrigerant by-pass valve is configuredto allow said refrigerant in said refrigerant-based thermal control loopto by-pass said second expansion valve, and wherein when saidrefrigerant valve is in said second mode said refrigerant by-pass valveis configured to allow said refrigerant in said refrigerant-basedthermal control loop to flow through said second expansion valve.
 4. Themulti-mode vehicle thermal management system of claim 3, wherein saidrefrigerant by-pass valve and said second expansion valve are combinedin an electronic expansion valve.
 5. The multi-mode vehicle thermalmanagement system of claim 1, further comprising a refrigerant by-passvalve, wherein said refrigerant by-pass valve in a first mode ofoperation couples said refrigerant-fluid heat exchanger to saidrefrigerant-based thermal control loop, and wherein said refrigerantby-pass valve in a second mode of operation decouples saidrefrigerant-fluid heat exchanger from said refrigerant-based thermalcontrol loop.
 6. The multi-mode vehicle thermal management system ofclaim 1, said passenger cabin thermal control loop further comprising asupplemental electric heater configured to heat said first heat transferfluid of said passenger cabin thermal control loop when electrical poweris connected to said supplemental electric heater.
 7. The multi-modevehicle thermal management system of claim 1, further comprising aradiator coupled to said drive train thermal control loop.
 8. Themulti-mode vehicle thermal management system of claim 7, furthercomprising a fan configured to force air through said radiator.
 9. Themulti-mode vehicle thermal management system of claim 7, furthercomprising a diverter valve, wherein said diverter valve in a firstposition couples said radiator to said drive train thermal control loopand allows at least a portion of said third heat transfer fluid to flowthrough said radiator, and wherein said diverter valve in a secondposition decouples said radiator from said drive train thermal controlloop and allows said third heat transfer fluid within said drive trainthermal control loop to by-pass said radiator.
 10. The multi-modevehicle thermal management system of claim 9, wherein said divertervalve in said first position allows a second portion of said third heattransfer fluid to by-pass said radiator, and wherein said diverter valvein a third position couples said radiator to said drive train thermalcontrol loop and allows said third heat transfer fluid to flow throughsaid radiator while preventing said second portion of said third heattransfer fluid from by-passing said radiator.
 11. The multi-mode vehiclethermal management system of claim 1, said vehicle battery packcomprising a plurality of batteries and a plurality of cooling conduitsin thermal communication with said plurality of batteries, wherein saidsecond heat transfer fluid within said battery thermal control loopflows through said plurality of cooling conduits.
 12. The multi-modevehicle thermal management system of claim 1, said at least one drivetrain component selected from the group consisting of a motor, agearbox, and a power inverter.
 13. The multi-mode vehicle thermalmanagement system of claim 1, further comprising a DC/DC converterthermally coupled to said drive train control loop.
 14. The multi-modevehicle thermal management system of claim 1, wherein said first heattransfer fluid is selected from the group consisting of water and watercontaining an additive, wherein said second heat transfer fluid isselected from the group consisting of water and water containing saidadditive, and wherein said third heat transfer fluid is selected fromthe group consisting of water and water containing said additive. 15.The multi-mode vehicle thermal management system of claim 14, whereinsaid additive is selected from the group consisting of ethylene glycoland propylene glycol.
 16. The multi-mode vehicle thermal managementsystem of claim 1, further comprising a coolant reservoir, wherein saidthird heat transfer fluid within said drive train thermal control loopflows into and out of said coolant reservoir.